How long to image the Ring Nebula with the Unistellar eQuinox 2
From a Bortle 6 suburban sky, the Unistellar eQuinox 2 needs about 6 min (96 subs of 4 s) for a solid image of the Ring Nebula. A quick look takes 2 min; a showpiece 26 min. Under a Bortle 3 rural sky the solid figure drops to 4 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 4% of the frame’s short side.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 1 min16 subs | 4 min63 subs | 17 min249 subs |
| Bortle 2Typical dark site | 1 min16 subs | 4 min64 subs | 17 min253 subs |
| Bortle 3Rural | 1 min17 subs | 4 min66 subs | 17 min261 subs |
| Bortle 4Rural / suburban transition | 1 min18 subs | 5 min70 subs | 19 min280 subs |
| Bortle 5Suburban | 1 min20 subs | 5 min78 subs | 21 min310 subs |
| Bortle 6Bright suburban | 2 min24 subs | 6 min96 subs | 26 min384 subs |
| Bortle 7Suburban / urban transition | 2 min33 subs | 9 min132 subs | 35 min525 subs |
| Bortle 8City | 3 min47 subs | 12 min187 subs | 50 min745 subs |
| Bortle 9Inner city | 5 min76 subs | 20 min304 subs | 1 h 21 min1,213 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 8 min of run time. The eQuinox 2’s battery (rated about 11 h) should cover it; a power bank still keeps the phone running the app alive. (Bortle 6, solid image; we allow 30% over the integration time.)
- USB-C power bank 20000mAh 5V 2AUnistellar asks for a 5 V 2 A output; PD is not needed.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
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Everything that fits the eQuinox 2 →
How it frames
The Ring Nebula is 1.4′ × 1′ across. The eQuinox 2 frames 0.76° × 0.57° at 1.33″ per pixel, so it fills 4% of the frame’s short side.
Filters
The Ring Nebula is an emission target, where a dual-band filter would normally cut the time several-fold from a lit sky, but the eQuinox 2 has no dual-band option: No built-in filter. Unistellar sells only a solar filter and says a third-party filter is at your own risk and voids the warranty. The figures above are for the No filter position, and a darker sky is the lever that remains.
About the Ring Nebula
A tiny, bright smoke ring. It is small in a smart scope but so bright per pixel that a few minutes show the ring; the faint outer halo is another matter.
M57, NGC 6720 · Planetary nebula in Lyra · magnitude 8.8 · 1.4′ × 1′ · best in Jun, Jul, Aug. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Planetary nebulae are small but intensely bright per pixel in OIII and H-alpha, so they respond very well to a dual-band filter and do not need much time for the main shell. The faint outer halos most of them have are a different proposition and need hours. Keep subs short if the central region saturates.
About the Unistellar eQuinox 2
A 114 mm Newtonian with five times the light grasp of a 50 mm refractor. Fixed 4 s subs put it in read-noise territory under dark skies, but the aperture carries it. The published field is 45.6′ × 34.2′, a crop of the sensor.
Fixed 4 s subs in Enhanced Vision; they cannot be changed. No built-in filter. Unistellar sells only a solar filter and says a third-party filter is at your own risk and voids the warranty.
The eQuinox 2 uses fixed 4 s subs, so the only levers you have are the sky you shoot from, the filter, and total time.
Stack across nights. Every smart scope app can continue a stack or you can combine the saved frames on a computer; the figures here are totals, not single-session limits.
Have an image of the Ring Nebula from a eQuinox 2? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Ring Nebula with the ZWO Seestar S50: 7 min from Bortle 6
- Ring Nebula with the ZWO Seestar S50 Pro: 8 min from Bortle 6
- Ring Nebula with the ZWO Seestar S30: 7 min from Bortle 6
- Ring Nebula with the ZWO Seestar S30 Pro: 8 min from Bortle 6
- Ring Nebula with the DwarfLab DWARF 3: 10 min from Bortle 6
- Ring Nebula with the DwarfLab DWARF mini: 8 min from Bortle 6
- Ring Nebula with the DwarfLab Draco: 15 min from Bortle 6
- Ring Nebula with the DwarfLab DWARF II: 25 min from Bortle 6
- Ring Nebula with the Vaonis Vespera II: 8 min from Bortle 6
- Ring Nebula with the Vaonis Vespera Pro: 17 min from Bortle 6
- Ring Nebula with the Vaonis Vespera 3: 7 min from Bortle 6
- Ring Nebula with the Vaonis Vespera Pro 2: 16 min from Bortle 6
- Ring Nebula with the Unistellar Odyssey: 28 min from Bortle 6
- Ring Nebula with the Celestron Origin: 5 min from Bortle 6
- Ring Nebula with the Celestron Origin Mark II: 5 min from Bortle 6
All telescopes for the Ring Nebula · All targets for the eQuinox 2